Rundāle Palace is one of the most outstanding monuments of Baroque and Rococo art in Latvia. It was built between 1736 and 1740 as a summer residence of Duke Ernst Johann of Courland.The Duchy of Courland-Semigallia, a vassal state of the Polish-Lithuanian Commonwealth, was founded in 1561 and it existed until 1795.In 1737 Ernst Johann Biron, a landlord in Courland and favorite of the Russian Empress Anna Ioannovna, became the Duke of Courland-Semigallia